Selected Balance Sheet Information (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Jan. 01, 2019	Dec. 31, 2018
Inventory:
Remotely operated vehicle parts and components	$ 103,022		$ 85,568
Other inventory, primarily raw materials	95,727		108,939
Total	198,749		194,507
Other Current Assets:
Prepaid expenses	44,488		60,858
Angolan bonds	10,179		10,179
Total	54,667		71,037
Accrued Liabilities:
Payroll and related costs	111,778		114,676
Accrued job costs	55,212		62,281
Income taxes payable	41,555		34,954
Current operating lease liability	19,626	$ 20,318	0
Other	85,648		95,022
Total	$ 313,819		$ 306,933